Partial funding is requested for the purchase of a Leica, TCS SP Confocal Laser Scanning Microscope (CLSM). The CLSM costs $303,616 of which $202,616 is requested in this application from NCRR with the remainder borne by funds from the St. Judge Children's Research Hospital (SJCRH). SJCRH is a research institution devoted to cross-disciplinary research relevant to the understanding, prevention and treatment of childhood cancer. The institution currently has 151 basic and clinical research investigators and 180 postdoctoral fellows supported by 200 technicians. The researchers are supported by 13 centralized core shared resources which are partially funded by the NIH Cancer Center Support Grant (CCSG). At present there is no CLSM as a shared resources at the SJCRH. There are two CLSMs owned by two individual investigators at SJCRH that are dedicated to their own research; these cannot meet the existing and projected demands of the research community at SJCRH. In this application 21 Principal Investigators supported by 28 NIH peer reviewed grants have described the precise areas of their investigation that would be immensely benefitted by the availability of a CLSM. Five of these investigators have been using the CLSM at a neighboring institution in the past three years and have published papers involving this usage. However, increased demand, scheduling conflicts, physical distance and lack of assistance in operating the CLSM have made it extremely difficult to continue this outside arrangement as well. In view of this high demand, funding for a new CLSM is requested. The new CLSM will be used as a shared instrument housed in an existing shared resource, the Electron Microscope Shared Resource (EMSR), and operated according to the existing guidelines. The Director of the EMSR and the Principal Investigator of this application, Dr. K. G. Murti, has substantial expertise in confocal imaging and related techniques. He will manage the CLSM with the help of a full-time Senior Research Technician providing the necessary expertise and guidance. The long-term of the CLSM will be financed by the institutional monies, chargeback fees, and CCSG.